Many mechanical devices exist that aid in the even dispensing and spreading of particulate material such as insecticide or fungicide dusts or granular particulate materials such as fertilizers. The simplest hand held spreaders for granulated products are manually operated by a rotary crank which either directly or indirectly turns a rotor which dispenses the particulate material from a hopper on the apparatus. U.S. Pat. No. 4,140,280 discloses one such apparatus. A portable battery-operated apparatus for such use is disclosed by U.S. Pat. No. 3,993,225. A somewhat different approach is disclosed by the invention of U.S. Pat. No. 4,678,377, in which a powder is contained in a flexible and manipulable pouch open at two ends through which a flow of air is forced by the drive mechanism to eject the dust.
One problem encountered in any mechanism for the dispensing of powdered material is the tendency of the material itself to lump and clog (as described in U.S. Pat. No. 4,712,716, which discloses a mechanism for metering dusting powder to assure even flow) or to bridge (as described in U.S. Pat. No. 4,071,170).
U.S Pat. No. 4,071,170 discloses a portable motor driven dusting apparatus which incorporates a mechanism to agitate the powdered material as it is being fed to the rotary blower to assure uniform rate of flow and avoid clogging or bridging problems.